Clamping dog for lathes



Oct. 8 1929. H. H. PEAcocK 1,731,216

CLAMPING DOG FOR LATHES Filed Dec. 13, 1927 Patented Oct. 8 1929 UNITEDSTATES PATENT OFFICE CLAMPING- DOG FOR LATI-IES Application filedDecember 13, 1927. Serial No. 239,698.

My invention relates to new and useful improvements in a clamping dogfor lathes, and has for its primary object to provide an exceedinglysimple and efiective device of this character which may be made indifferent class to accommodate work of diferent dimensions, but whichmay be used on work of a smaller diameter than that for which the clampis specifically constructed by the use of packing.

Another object of the invention is to provide a clamping dog which isindependent or free of the lathe but actuated thereby when in use so asto firmly clamp the work.

A further object of the invention is to provide a clamping dogconsisting of a collar of unique construction provided with twocommunicating passages, one of which is designed to receive the work,while in the other is rotatably mounted a cam to clamp upon the work anda portion of said cam carries a locking member to lock or hold the camin different adjusted positions, particularly when in an inoperativecondition.

A still further object of the invention is to provide for lifting theclamp dog as a whole.

With these ends in view, this invention consists in the details ofconstruction and combination of elements hereinafter set forth and thenspecifically designated by the claim.

In order that those skilled in the art to which this inventionappertains may understand how to make and use the same, I will describeits construction in detail, referring by numerals by the accompanyingdrawings forming a part of this application, in which:

Fig. 1 is a perspective view of the head of a lathe, a piece of work andmy improved clamping dog connected therewith.

Fig. 2 is a longitudinal sectional view through the. clamping collarwith the cam illustrated in elevation and shown in position.

Fig. 3 is a side elevation of the cam.

Fig. 4 is a face view thereof.

Fig. 5 is an edge view of the collar.

Fig. 6 is a face view of the same.

In carrying out my invention as herein embodied, 7 represents theclamping dog collar of substantially oval shape and having two passages8 and 9 communicating with each other, the latter passage being for thereception of the piece of work such as a rod, shaft or other structurecircular in cross section as shown at 10, Fig. 1. Within the passage 8is rotatably mounted a cam 11 including a body 11" and flanges 11 andthe body is provided with a true circular edge portion 12 for coactionwith the inner edge surface of the collar within the passage 8, whilethe flanges are provided with sigmoid surfaces 13, the convex portion ofwhich acts as the clamping element for engagement with the work whilethe concave portion provides for spacing the cam from the :work when theclamping dog is being placed on said work The cam is preferably rotatedthrough the medium of an arm 15 which projects there'- from to beengaged by the driver 16, suitably mounted on the lathe head 17 and thisarm may be held or locked in different positions by a locking member 18pivoted on the arm 15 and coacting with the collar. v

The cam is also provided with a lifting 'hole 19 into which a personsfinger may be inserted if the clamping dog is of small size, or intowhich an eye bolt or other suitable connection may be temporarilyinserted so that a crane hook may be attached thereto if the device isof very large size.

In order to position packing elements to decrease the effective size ofthe passage 9, I provide projections 20 within the passage 9 andprojecting from the inner surface of the collar and said projections areso arranged as to be outside of the space occupied by the largest pieceof work which may be accommodated by the clamp, such work beingindicated in dotted lines in Fig. 6.

In actual practice, the clamping dog is placed upon the work 10 prior tothe work being finally positioned in the lathe after which said work isset and the clamping dog then moved into proximity to the head 17 and sopositioned that the driver 16 will engage the arm when the lathe beginsto 0perate.

As soon as the driver engages the arm 15 the cam 11 will be rotateduntil the convex portions of the sigmoid surfaces engage the Work, thusforcing said work snugly against the inner edges or surfaces of thecollar in the region of the passage 9, thus firmly clamping the dog onthe work.

If the work is smaller than that indicated by the dotted circle in Fig.6, then suitable blocks or strips are placed within the passageway 9 sothat the ends of said blocks rest against the projections 20, and sincethe clamping dog need not be central relative to the work, and since ithas nothing to do. with centering said Work, the packing blocks orstrips do not have to be equal on both sides.

Where the clamping dog is used on the finished or polished surface of apiece of work, any suitable protecting device may be placed between thework and the contracting walls of the clamping dog, said protectingdevice generally being a strip of soft metal, such as copper, but unlessthe surface is a highly finished one, the protecting device is notneeded because there is little likelihood of the clamping dog marringthe surface.

Of course I do not wish to be limited to the exact details ofconstruction as herein shown, as these may be varied within the limitsof the appended claim without departing from the spirit of my invention.

Having thus fully described my invention, what I claim as new and usefulis In a device of the land described, a collar provided with a workreceiving passageway and a bearing, a cam body rotatably mounted in thebearing, cam flanges at the ends of the body and lying on oppositefacesof the collar, a cam arm projecting from one of the flanges, andmeans carried by said arm for coaction with the edge of the collar tohold said cam in different adjusted positions.

In testimony whereof, I have hereunto affixed my signature. 1

HOWARD H. PEAGOCK.

